Category Archives: dog breeds

The evolution of dog breeds

When people migrate, Canis familiaris travels with them. Piecing together the details of those migrations has proved difficult because the clues are scattered across the genomes of hundreds of dog breeds. However, in a study published April 25, 2017 in Cell Reports, researchers have used gene sequences from 161 modern breeds to assemble an evolutionary tree of dogs.

The map of dog breeds, which is the largest to date, unearths new evidence that dogs traveled with humans across the Bering land bridge, and will likely help researchers identify disease-causing genes in both dogs and humans.

Cladogram of 161 Domestic Dog Breeds

Cladogram of 161 Domestic Dog Breeds

The study highlights how the oldest dog breeds evolved or were bred to fill certain roles. “First, there was selection for a type, like herders or pointers, and then there was admixture to get certain physical traits,” says study co-author and dog geneticist Heidi Parker of the National Institutes of Health (NIH). “I think that understanding that types go back a lot longer than breeds or just physical appearances do is something to really think about.”

Most popular breeds in America are of European descent, but in the study, researchers found evidence that some breeds from Central and South America — such as the Peruvian Hairless Dog and the Xoloitzcuintli– are likely descended from the “New World Dog,” an ancient canine sub-species that migrated across the Bering Strait with the ancestors of Native Americans. Scientists have previously reported archaeological evidence that the New World Dog existed, but this study marks the first living evidence of them in modern breeds.

“What we noticed is that there are groups of American dogs that separated somewhat from the European breeds,” says study co-author Heidi Parker of the NIH. “We’ve been looking for some kind of signature of the New World Dog, and these dogs have New World Dogs hidden in their genome.” It’s unclear precisely which genes in modern hairless dogs are from Europe and which are from their New World ancestors, but the researchers hope to explore that in future studies.

Other results were more expected. For instance, many breeds of “gun dogs,” such as Golden Retrievers and Irish Setters, can trace their origins to Victorian England, when new technologies, such as guns, opened up new roles on hunting expeditions. Those dogs clustered closely together on the phylogenetic tree, as did the spaniel breeds. Breeds from the Middle East, such as the Saluki, and from Asia, such as Chow Chows and Akitas, seem to have diverged well before the “Victorian Explosion” in Europe and the United States.

Herding breeds, though largely European in origin, proved to be surprisingly diverse. “When we were looking at herding breeds, we saw much more diversity, where there was a particular group of herding breeds that seemed to come out of the United Kingdom, a particular group that came out of northern Europe, and a different group that came out of southern Europe,” says Parker, “which shows herding is not a recent thing. People were using dogs as workers thousands of years ago, not just hundreds of years ago.”

Different herding dogs use very different strategies to bring their flocks to heel, so in some ways, the phylogenetic data confirmed what many dog experts had previously suspected, the researchers noted. “What that also tells us is that herding dogs were developed not from a singular founder but in several different places and probably different times,” says the study’s senior co-author and dog geneticist Elaine Ostrander, also of the NIH.

Ostrander and her colleagues have spent years sequencing dog genomes but can also frequently be found out in the field at dog shows, recruiting dog owners to participate in the study. “If we see a breed that we haven’t had a good sample of to sequence, we definitely make a beeline for that owner,” says Ostrander. “And say, ‘Gosh, we don’t have the sequence of the Otterhound yet, and your dog is a beautiful Otterhound. Wouldn’t you like it to represent your breed in the dog genome sequence database?’ And of course, people are always very flattered to say, “Yes. I want my dog to represent Otterhound-ness.” All of the dog sequences in the study are from dogs whose owners volunteered, Ostrander says. Over half the dog breeds in the world today still have not been sequenced and the researchers intend to keep collecting dog genomes to fill in the gaps.

Understanding dogs’ genetic backstory also has practical applications. Our canine compatriots fall victim to many of the same diseases that humans do — including epilepsy, diabetes, kidney disease, and cancer — but disease prevalence varies widely and predictably between breeds, while it is more difficult to compartmentalize at-risk human populations. “Using all this data, you can follow the migration of disease alleles and predict where they are likely to pop up next, and that’s just so empowering for our field because a dog is such a great model for many human diseases,” says Ostrander. “Every time there’s a disease gene found in dogs it turns out to be important in people, too.”

Source:  ScienceDaily

Full journal article available here

Canine hereditary diseases more common than previously indicated

Comment from me (DoggyMom):  I am particularly pleased to read in this media release that the researchers are recommending cooperation between industry, science and laypersons.  As a canine massage therapist, I have found the traditional ‘evidence-based medicine’ fraternity reluctant to involve specialists in other fields and particularly those that are not research scientists or veterinarians.
It is my hope that we can cooperate more in the future as we undertake research into dog health and behavior because by sharing different points of view and expertise, we develop a richer range of options in problem-solving.
Kathleen Crisley, specialist in dog massage, rehabilitation and nutrition/food therapy, The Balanced Dog, Christchurch, New Zealand

Genoscoper Ltd. has published in cooperation with the researchers of University of Helsinki and Pennsylvania (USA) the most comprehensive study on canine hereditary disorders so far. The research brings new information about genetic disorders causing diseases in different dog breeds. The results can be utilized both in dog breeding and veterinary diagnostics. The study was published on PLOS ONE on 15 August 2016.
Dogs have more hereditary diseases than previously thought

Dogs have more hereditary diseases than previously thought. Photo: Eeva Karmitsa

– We noted that surprisingly many canine inherited disorders are actually more widespread than indicated by their original discovery studies, which opens up the door for several future scientific investigations, explains senior author Dr. Hannes Lohi from the University of Helsinki canine genetics research group.

– The technological potential to test a dog for multiple inherited disorders at once has existed for several years. The challenge is to harness that potential for practical use in improved veterinary disease diagnostics, sustainable breeding selections, personalized pet care, and canine genetics research, says lead author Dr. Jonas Donner of Genoscoper Laboratories. Genoscoper Ltd. is a Finnish company specialized in animal genetics and gene testing.

By testing nearly 7000 dogs representing around 230 different breeds for predisposition to almost 100 genetic disorders, the research team observed that 1 in 6 dogs carried at least one of the tested disease predisposing genetic variants in their genome. Moreover, 1 in 6 of the tested genetic variants was also discovered in a dog breed in which it had not previously been reported in the scientific literature. Through clinical follow up of dogs genetically at risk, the research team was able to confirm that several disorders cause the same disease signs also in other than previously described breeds.

– Precisely as we humans, every dog is likely to carry genetic predisposition for some inherited disorder, so we expect these numbers to grow as the numbers of tested disease variants, breeds, and dogs further increase, confirms Dr. Donner.

Co­oper­a­tion is key to health­ier dogs

– Our study demonstrates the importance of collaboration between different contributors – academics, industry and dog fanciers – to reach novel resources that not only enable better understanding of canine genetic health across breeds but also provides viable solutions to improve the health.  The published study provides also an excellent example of the added value of research collaborations between academia and industry in a form that leads to a powerful innovation that start changing the everyday practice in veterinary medicine and improves the welfare of our dogs, says Lohi.

Ge­netic panel screen­ing de­liv­ers res­ults

The study concludes that comprehensive screening for canine inherited disorders represents an efficient and powerful diagnostic and research discovery tool that has a range of applications in veterinary care, disease research, and dog breeding. The authors emphasize that availability of complex DNA-based information is important progress for improvement of the health of purebred dogs, but it should be utilized in combination with other established approaches that promote sustainable breeding and benefit breed health.

The full scientific publication can be accessed here.

Reference:
Donner J, Kaukonen M, Anderson H, Möller F, Kyöstilä K, Sankari S, Hytönen MK, Giger U and Lohi H. Genetic panel screening of nearly 100 mutations reveals new insights into the breed distribution of risk variants for canine hereditary disorders. PlosONE, 1(8): e0161005. doi:10.1371/journal.pone.0161005, 2016.

Source:  University of Helsinki media release

Study demonstrates rapid decline in male dog fertility, with potential link to environmental contaminants

A study led by researchers at The University of Nottingham has discovered that the fertility of dogs may have suffered a sharp decline over the past three decades.

The research, published in the academic journal Scientific Reports, found that sperm quality in a population of stud dogs studied over a 26-year period had fallen significantly.

The work has highlighted a potential link to environmental contaminants, after they were able to demonstrate that chemicals found in the sperm and testes of adult dogs – and in some commercially available pet foods – had a detrimental effect on sperm function at the concentrations detected.

Semen study

Researchers believe that the latest results showing that dogs’ quality of semen has diminished may offer a new piece of the puzzle over the reported significant decline in human semen quality. Credit: © jurra8 / Fotolia

As ‘man’s best friend’ and closest companion animal, the researchers believe that the latest results may offer a new piece of the puzzle over the reported significant decline in human semen quality – a controversial subject which scientists continue to debate.

Dr Richard Lea, Reader in Reproductive Biology in the University’s School of Veterinary Medicine and Science, who led the research said: “This is the first time that such a decline in male fertility has been reported in the dog and we believe this is due to environmental contaminants, some of which we have detected in dog food and in the sperm and testes of the animals themselves.

“While further research is needed to conclusively demonstrate a link, the dog may indeed be a sentinel for humans – it shares the same environment, exhibits the same range of diseases, many with the same frequency and responds in a similar way to therapies.”

The study centred on samples taken from stud dogs at an assistance dogs breeding centre over the course of 26 years. Professor Gary England, Foundation Dean of the School of Veterinary Medicine and Science and Professor of Comparative Veterinary Reproduction, who oversaw the collection of semen said: “The strength of the study is that all samples were processed and analysed by the same laboratory using the same protocols during that time and consequently the data generated is robust.”

The work centred on five specific breeds of dogs – Labrador retriever, golden retriever, curly coat retriever, border collie and German shepherd – with between 42 and 97 dogs studied every year.

Semen was collected from the dogs and analysed to assess the percentage of sperm that showed a normal forward progressive pattern of motility and that appeared normal under a microscope (morphology).

Over the 26 years of the study, they found a striking decrease in the percentage of normal motile sperm. Between 1988 and 1998, sperm motility declined by 2.5 per cent per year and following a short period when stud dogs of compromised fertility were retired from the study, sperm motility from 2002 to 2014 continued to decline at a rate of 1.2% per year.

In addition, the team discovered that the male pups generated from the stud dogs with declining semen quality, had an increased incidence of cryptorchidism, a condition in which the testes of pups fail to correctly descend into the scrotum.

Sperm collected from the same breeding population of dogs, and testes recovered from dogs undergoing routine castration, were found to contain environmental contaminants at concentrations able to disrupt sperm motility and viability when tested.

The same chemicals that disrupted sperm quality, were also discovered in a range of commercially available dog foods – including brands specifically marketed for puppies.

Dr Lea added: “We looked at other factors which may also play a part, for example, some genetic conditions do have an impact on fertility. However, we discounted that because 26 years is simply too rapid a decline to be associated with a genetic problem.”

Over the past 70 years, studies have suggested a significant decline in human semen quality and a cluster of issues called ‘testicular dysgenesis syndrome’ that impact on male fertility which also include increased incidence of testicular cancer, the birth defect hypospadias and undescended testes.

However, declining human semen quality remains a controversial issue – many have criticised the variability of the data of the studies on the basis of changes in laboratory methods, training of laboratory personnel and improved quality control over the years.

Dr Lea added: “The Nottingham study presents a unique set of reliable data from a controlled population which is free from these factors. This raises the tantalising prospect that the decline in canine semen quality has an environmental cause and begs the question whether a similar effect could also be observed in human male fertility.”

Source:  University of Nottingham media release

Limber tail – it’s more common than previously thought

Limber tail photo

Limber tail is a condition that affects mostly large working dog breeds.  It’s a distressing condition that causes the tail to become limp and painful and it’s official name is acute caudal myopathy.

A research team at the University of Edinburgh compared 38 cases of limber tail that were identified from owners’ reports about their dogs’ health with 86 dogs that had no tail symptoms.

Their goal was to gain insight into habits and lifestyle factors that might explain why some dogs are affected and not others.

The majority of dogs in the study were pets but those affected by limber tail were more likely to be working dogs, they found.

Swimming has previously been thought to be a risk factor for limber tail, which is sometimes known as ‘swimmers’ tail’. Some but not all of the affected dogs had been swimming prior to the onset of symptoms, the study found.

Dogs with the condition were more likely to live in northern areas, lending support to anecdotal reports that limber tail is associated with exposure to the cold.

Labradors that had suffered limber tail were more likely to be related to each other than unaffected dogs, which may indicate an underlying genetic risk.

Experts hope that further studies will identify genes associated with the condition, which could one day help breeders to identify animals that are likely to be affected. Over time, this could help to reduce the prevalence of the disease.

The symptoms usually resolve within a few days or weeks so many cases are not reported to vets. This may be why it has been so underestimated in the past. However, owners report that it can be very painful and distressing for the animals.

The study is the first large-scale investigation of limber tail and was conducted as part of the Dogslife project, which follows the health and wellbeing of more than 6000 Labradors from across the UK.  (Note:  the disorder also commonly affects English Pointers, English Setters, Foxhounds and Beagles.)

The study has been published in the Veterinary Record.

Source:  University of Edinburgh media release

Scientists warn about health of English Bulldog

According to new research it could be difficult to improve the health of the English bulldog, one of the world’s unhealthiest dog breeds, from within its existing gene pool. The findings will be published in the open access journal Canine Genetics and Epidemiology.

The English bulldog’s limited genetic diversity could minimize the ability of breeders to recreate healthy phenotypes from the existing genetic stock, which were created by human-directed selection for specific desired physical traits.

English Bulldog

Many large regions of the bulldog’s genome have been altered to attain the extreme changes in its outward appearance. This includes significant loss of genetic diversity in the region of the genome that contains many of the genes that regulate normal immune responses. Despite this, the English bulldog is one of the most popular dog breeds, particularly in the US, where the bulldog was the fourth most popular pure breed in 2015.

Lead author, Niels Pedersen from Center for Companion Animal Health, University of California, US, said: “The English bulldog has reached the point where popularity can no longer excuse the health problems that the average bulldog endures in its often brief lifetime. More people seemed to be enamoured with its appearance than concerned about its health. Improving health through genetic manipulations presumes that enough diversity still exists to improve the breed from within, and if not, to add diversity by outcrossing to other breeds. We found that little genetic ‘wiggle room’ still exists in the breed to make additional genetic changes.”

Pedersen adds: “These changes have occurred over hundreds of years but have become particularly rapid over the last few decades. Breeders are managing the little diversity that still exists in the best possible manner, but there are still many individuals sired from highly inbred parents. Unfortunately eliminating all the mutations may not solve the problem as this would further reduce genetic diversity. We would also question whether further modifications, such as rapidly introducing new rare coat colors, making the body smaller and more compact and adding more wrinkles in the coat, could improve the bulldog’s already fragile genetic diversity.”

This is the first broad-based assessment of genetic diversity in the English bulldog using DNA analysis rather than pedigrees. DNA analysis is needed to measure, monitor and maintain genetic diversity. This has been done in several other breeds including Standard and Miniature Poodles, American Golden Retrievers, and American and European Italian Greyhound.

The researchers sought to identify whether there is enough genetic diversity still existing within the breed to undertake significant improvements from within the existing gene pool. The researchers examined 102 English bulldogs, 87 dogs from the US and 15 dogs from other countries. These were genetically compared with an additional 37 English bulldogs presented to the US Davis Veterinary Clinical Services for health problems, to determine that the genetic problems of the English bulldogs were not the fault of commercial breeders or puppy mills.

Many Swiss breeders have started to outcross the breed with the Olde English Bulldogge (an American breed) to create the Continental Bulldog, hoping to improve the breed’s health. Although outcrossing the English bulldog could improve its health, many breeders feel that any deviations from the original standard will no longer be an English bulldog.

The breed started from a relatively small genetic base with a founder population of 68 individuals after 1835 and has undergone a number of human created artificial bottlenecks (drastic reductions in population size). These could also have greatly diminished genetic diversity.

Source:  BioMed Central media release

Cross-breeding to eradicate Chiari syndrome

In a new study published in the journal PLOS ONE, scientists from the University of Surrey, working with an experienced breeder in the Netherlands, examined how the skull and brain of toy dogs change when a Brussels Griffon with Chiari-like malformation is crossed with an Australian Terrier.  The succeeding hybrid puppy is then back crossed to a Brussels Griffon to give some of the features of the Brussels Griffon, but keeping the longer skull of the Australian Terrier.

Griffon and cross breed

Second-generation backcross and purebred Brussel Griffon Sire Photo credit: Henny van der Berg

The results from the study showed it is possible to breed a dog which had the external features of a short-nosed Brussels Griffon and reduce the risk of Chiari malformation, a debilitating condition found in toy dogs and affecting 1 in 1,280 humans.  The disease is characterised by premature fusion of skull bones forcing parts of the brain to push through the opening in the back of the skull causing fluid filled cavities to develop in the spinal cord. Chiari malformation causes headaches, problems with walking or even paralysis and has become prevalent in some toy breed dogs as a result of selective breeding.

The breeder, Henny van der Berg proposed the project idea after an accidental mating between two of her dogs.  The four-year study analysed five traits on magnetic resonance images (MRI) scans and how they changed generation by generation in the family of 29 dogs.  Using a careful selection of head shape and MRI scans over two generations, the findings revealed it was possible to breed a dog which had the external features of a Brussels Griffon, but is less susceptible to Chiari malformation.

“This is a true collaboration with breeders and researchers working together and using their expertise to improve the health of dogs,” said Dr Clare Rusbridge from the University of Surrey.

“Our study investigated how the characteristics of this disease is inherited in the family.  Such knowledge could help in tackling this debilitating disease in toy dog breeds.  We hope our research will help develop more sophisticated ways of screening and improve breeding guidelines by creating robust breeding values.”

The team at the University of Surrey is now collaborating with geneticists at the University of Montreal, and correlating the skull and brain traits visualised on magnetic resonance images with the dog genome. This information will then be translated to humans.

Source:  University of Surrey media release

My other posts about Chiari malformation include:

Joey and the Pit Bull


People who have autism are often misunderstood.  So are Pit Bulls.  These two make a great pair.

Kathleen Crisley, specialist in dog massage, rehabilitation and nutrition/food therapy, The Balanced Dog, Christchurch, New Zealand